Nineteen studies were included in the review (n=4,388 implants): nine retrospective studies and 10 prospective studies. Kappa scores for interobserver agreement for study selection were 0.76 at the title level and 0.53 at the abstract level. Mean follow-up in the studies was 3.1 years (range one to five years). Percentage dropout ranged from 0% to 10%, but dropout rates were not reported in 10 studies.
Of the 103 implants that were lost, 55 implants were lost prior to loading and 28 implants were lost after at least one year of function.
The summary estimated failure rate per 100 implant years was 2.48 (95% CI 1.37 to 4.49). The summary estimate for survival after three years was 92.8% (95% CI 87.4% to 96%). When studies with bone height of more than 8mm were excluded, survival rate of implants decreased to 91.8% (95% CI 85.7% to 95.4%).
Annual failure rates were calculated for nine studies (770 implants). The estimated annual failure rate was 3.71% (95% CI 1.21% to 11.38%) which corresponded to 10.5% (95% CI 3.6 to 28.9%) of patients experiencing implant loss over three years.
The most common surgical complication was Schneiderian membrane perforation, which varied between 0% and 21.4% in eight studies that reported this outcome. Postoperative infections were the most common postoperative complication and ranged between 0% and 2.5% (six studies, 884 implants). Other complications included postoperative haemorrhage, nasal bleeding, blocked nose, haematomas and loosening of cover screws resulting in suppuration.